Chromosome 11 contains genes encoding, for example, KCNQ1, a voltage-gated potassium channel; IPL, a homolog of a mouse apoptosis-inducing entity; human achaete-scute homolog 2 (HASH2), human SMS3, human tumor suppressing subtransferable candidate 6 (TSSC6), human ribosomal protein L26 (RIBO26), cluster of differentiation antigen 81 (CD81) and tumor suppressing subtransferable candidate 4 (TSSC4). Human achaete-scute homolog 2 (HASH2), human SMS3, human tumor suppressing subtransferable candidate 6 (TSSC6), human ribosomal protein L26 (RIBO26), cluster of differentiation antigen 81 (CD81) and tumor suppressing subtransferable candidate 4 (TSSC4) are discussed in further detail below. Genes for the latter six proteins are located in the p15 region of chromosome 11, a region known to be associated with the Beckwith-Wiedemann Syndrome (Itoh et al. Am. J. Genet. 92, 111-6, 2000) and some childhood tumors.
Beckwith-Wiedemann Syndrome is characterized by pre and postnatal overgrowth up to 160% of normal birthweight, macroglossia, hypoglycemia, hemi-hypertrophy and childhood tumors, such as Wilm's tumor (Reik et al., 1998, Trends Genet. 13:330-334). This syndrome appears to be associated with deregulation of imprinting. Imprinted genes are genes that are predominantly expressed from one of the parental chromosomes. There appears to be two imprinted subdomains, since the imprinted gene domain of 11p15 contains at least two imprinted subdomains (Lee et al., 1999, Hum. Mol. Genet. 8:683-690). Mosaicism may also play some role in the Beckwith-Wiedemann Syndrome phenotype and may explain the variable phenotypes in Beckwith-Wiedemann Syndrome patients (Itoh et al., 2000, Am. J. Med. Genet. 92:111-116).
Human Achaete-Scute Homolog 2 (HASH2)
HASH2 is a basic helix-loop-helix protein that serves as a critical transcription factor for the development of the trophectoderm. Mice deficient in the HASH2 homolog, MASH2, die 10 days postcoitum due to placental failure (Guillemot et al., Nature 371, 333-6, 1994).
Human Tumor Suppressing Subtransferable Candidates 4 and 6 (TSSC4 and TSSC6)
Both TSSC 4 and TSSC6 are believed to function as tumor-suppressing proteins in that the genes are among the genes of a subchromosomal fragment that suppresses in vitro growth of the rhabdomyosarcoma cell line RD (Koi et al., Science 260, 361-4, 1993).
Human Ribosomal Protein L26 (RIBO26)
RIBO26 is one of the approximately 80 proteins that compose the human ribosome (Kenmochi, N. et al., Genome Res. 8, 509-23, 1998). It has been found in mice to be induced by LPS and IFN gamma but is down regulated by TNF-alpha (Segade et al., 1996, Life Sci. 58:277-285).
Human Cluster of Differentiation Antigen 81 (CD81)
CD81 (also called TAPA1) binds the E2 envelope protein of the human hepatitis C virus and is believed to play a role in hepatitis C infection (Pileri et al., Science 282, 938-41, 1998). CD81 also appears to play a role in T cell activation (Witherden et al., 2000, J. Immunol. 165:1902-1909).